STATEN ISLAND, N.Y. -- The discovery of a suspicious suitcase brought the NYPD’s Bomb Squad on the double to Port Richmond Monday night, leading officers to rope off one block and evacuate families living on another for several hours.

The unnerving episode began at 9:30 p.m. on Barrett Avenue near its intersection with Decker Avenue, just behind the Forest Avenue Shoppers Town strip mall, and by about 10:15 p.m., police had deployed a Bomb Squad robot.

Police evacuated a row of houses along Cornell Street on the side closest to Barrett; later, members of the NYPD’s Community Affairs Bureau briefed a group of residents standing outside.

The officers told the residents about the black suitcase, and said that its contents seemed to resemble the plastic explosive C4. That led the police Emergency Services Unit and Bomb Squad to rope off the area as a precaution.

Police allowed residents to return to their homes at about 12:15 a.m., though Barrett Avenue remained a crime scene into the early morning.

An NYPD spokesman said the suitcase turned out not to contain anything explosive, though he couldn’t say, as of 1 a.m. Tuesday, what it did contain.

That aspect of the case remains under investigation, the spokesman said.

After the FDNY and several police units cleared out, investigators — including some assigned to the NYPD’s Arson and Explosives Unit — remained on the scene behind the white and blue cordon.

Police at 9:30 p.m. “knocked on the door and said we had to leave. It was for our safety, and they couldn’t say any more,” said Nieves Pavia, who was home on Cornell Street with her brother, two sisters, 12-year-old daughter and 8-year-old son.

Her son, Danny, said he’d planned to spend the night watching a new cartoon series.

“I missed my show! ‘Uncle Grandpa!’” Danny said, as he sat on a curb with his family near the corner of Cornell Street and Decker Avenue.

“They knocked on our door at 9:30 and they told us that there was an explosive device, that they think, and that as a precaution we have to evacuate,” said Kelly Modzelewski, who also lives on Cornell. She and her husband were home with their 1-year-old daughter.

“She’s with my mom. I want to make sure she’s safe and we don’t have to worry about anything.”